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Jason Venkiteswaran

Assistant Professor, Geography and Environmental Studies

I am curious as to why the environment is the way it is and to figure out what is actually happening in lakes and streams. Why are some lakes so dark and others so light in colour? Where do all the nutrients we add to farm fields to grow crops go? What do human changes to the landscape mean for how our rivers and lakes work?

Like most researchers, we stumble into a specific field of study as opportunities present themselves. As a graduate student, I had the great opportunity to work on whole-ecosystem experiments at the International Institute for Sustainable Development (IISD) Experimental Lakes Area. The project focused on determining how the amount of carbon (vegetation, soil, peat) on a landscape controlled the amount of greenhouse gases produced and mercury that accumulated in fish when we create hydroelectric reservoirs.

This work leads my interests in understanding the processes or mechanisms that produce the things we observe in the environment and the ability to broaden my investigations from carbon (such as the greenhouses gases carbon dioxide and methane) to other elements and nutrients like nitrogen and oxygen. These are all critically biologically important elements required for life and can be used to assess human impacts on the environment. Ultimately, I want to turn some of this research into tools we can employ to identify both degradation and recovery of ecosystems.

My new paper in the journal Facets is part of the work to understand how much influence atmospheric deposition and forest catchments have on the sediment that gets deposited at the bottom of boreal lakes. We use this sediment record as a way to travel back in time to understand what lakes and general environment were like centuries and millennia ago. Boreal lakes are the great recorders of history around the world, but how much lake history versus catchment history do they record? And do they record it differently for other elements like carbon and nitrogen?

For me, there are two surprising parts of this paper:

Lakes in the middle of the bush in northwestern Ontario are no longer sites of low nitrogen deposition. They are no longer the pristine isolated lakes we think they are from a nitrogen standpoint; and

The very wide range of isotope values of the nitrogen in deposition means we need to know how this affects our understanding of aquatic ecology with isotopes and how we interpret lake history with isotopes in lake sediments.